The present invention relates to inflatable/deflatable devices, and in particular to such a device for use in a body-implantable heart-assist pump.
A body-implantable heart-assit pump here denotes a pumping apparatus adapted to be connected across major aortae in the body to augment the pumping capacity of the heart. Such apparatus generally includes flexible inner and outer sleeves, the inner sleeve being connectable at its opposite ends to appropriate aortae. Positioned between the inner and outer sleeves is an inflatable/deflatable balloon which is connected by a fluid-exchange tube to a fluid-driving unit generally carried outside the body. As the balloon is alternately inflated and deflated under the influence of a recurrent, cyclic supply and exhaust of fluid from the driving unit, the inner sleeve is alternately closed and opened, and blood is, accordingly, pumped through the inner sleeve.
Heretofore, inflatable/deflatable balloons designed for the above-described use have had a generally stocking-type construction, providing an elongate, cylindrical structure closed at one end and communicating at the other end with a fluid-exchange tube. Such prior art balloons, when inflated, have a generally circular cross section, and as a result, may migrate undesirably during operation. Such migration, in the extreme, can seriously impair the efficiency of a pumping operation.
It is, therefore, a principal object of the present invention to provide for use in a heart-assist pump, an inflatable/deflatable device having a construction which substantially prevents the above-discussed migrating tendency.
Yet another object of the invention is to provide such a device which can be distended preferentially in a desired direction.
Another object of the invention is to provide such a device which, when deflated, has a generally curved cross-sectional shape conforming to adjoining wall portions of the sleeves forming a pump of the type mentioned.
A preferred embodiment of the invention includes a balloon device having an inflatable/deflatable central portion, and a noninflatable, generally planar marginal portion joined thereto. The central and marginal portions are formed through the marginal joinder of a pair of flexible fluid-impervious sheets, with the marginal portion including stretches distributed along opposite sides of the central portion. The two sheets have different flexibilities, such that inflation occurs preferentially in the direction of the sheet having the greater flexibility. Further, the two sheets are joined and dimensioned in such a way to produce a generally curved transverse cross section for the device when the same is in a relaxed state.
These and other objects and features of the present invention will now be more fully described with reference to the detailed description of the following embodiments of the invention, and the accompanying drawings.